I own a cateye strada wireless one, which I use on a roadie (covered nearly 3000 miles – still on the original batteries), coped with the odd shower without issue. Fitting was fairly easy too.
I also use an i-got-u GPS logging device (I own the GT-600 unit) to track where I’ve been (I don’t own a smart phone & didn’t want to shell out for a full GPS). It gives me stats on average speed vs distance/time, pace, altitude vs distance/time, max speed, average speed, calories burnt etc. I use it for both Roadie & MTB duties. It doesn’t give you feedback whilst riding (download to PC once you’ve finished). Think I paid about £55 for the one I’ve got.
Very happy with both of these.